The present invention relates to improvements in rod-shaped smokers' articles in general, and more particularly to improvements in rod-shaped articles of the type having a relatively soft or non-existent core and a relatively dense outer layer of smokable particulate material. The invention also relates to a novel method and to a novel apparatus for the making of such articles.
German Pat. No. 11 64 907 discloses a cigarette which has a centrally extending air-conveying channel. The channel is formed by a stationary mandrel which extends axially through the rod-shaped filler of the cigarette. The mandrel continuously discharges into the particles of smokable material a hardening agent which is supposed to ensure that the channel will remain intact upon extraction of the mandrel.
A cigarette which has an axially extending channel or a core of relatively low density (as compared with the density of the surrounding outer layer) is disclosed in British Pat. No. 1,086,443.